The invention relates to a cutting tool with a cutting plate comprising on its circumference at least one cutting tooth, which has a central through hole terminating on a front face with a hole enlargement and a cylindrical, non circular coupling surface intended for the form-fit contact on a fitting countersurface of a holder, which comprises an axially parallel screw hole and the cutting plate is secured on the holder by screw connection with a head screw penetrating its through hole.
DE-A-31 19 189 shows a cutting tool. The cutting plate has a projection with square contour and is slid into a slit formed between two jaws of the holder. The slit comprises a slide channel for the projection of the cutting plate. The hole enlargement is not located in the cutting plate but rather in one of the jaws of the holder. Two opposing side faces of the projection form the coupling surfaces which, together with the side faces of the insertion channel as countersurfaces, are intended to secure the cutting plate on the holder against rotation. The projection does not prevent the cutting plate from becoming linearly displaced on the holder. A centering function cannot be assumed by the projection with its coupling surfaces. This is the function of the fastening screw.
DE-C-38 16 301 shows a cutting tool in which the cutting plate also has a projection whose side faces represent form-fitting coupling surfaces. In this case the projection has a square or rhomboidal contour and two side faces, abutting each other at an angle, of the projection come into contact over a portion of their lengths with complementary counterfaces of the holder. Here too, centering between cutting plate and holder is absent. The head screw must assume this centering and for that reason is under high load.
DE-C-34 48 086 shows a cutting tool in which on one front face of the cutting plate radial ribs are provided which form-fittingly engage corresponding grooves of the holder. The ribs have a trapezoidal cross section. The cutting plate is centered, however, at high cutting forces the danger of breakage of the ribs exists and the screws and their screw seat in the holder are under high load.
DE-A-40 26 651 shows a cutting tool in which the cutting plate is fastened on the holder by means of a separate coupling bolt. Between cutting plate and holder no direct coupling engagement exists, rather a portion or the through hole is implemented as coupling surface whose contour forms a rounded triangular concave polygon. The holder has at its end an identically contoured coupling surface and the tie bolt has a complementary countersurface whose contour thus forms a triangular convex polygon. For reasons of construction, the cutting plate cannot be fastened on the holder by means of a screw, rather the tie bolt requires a complicated clamping device in a widened head of the holder there is play in the connections between the cutting plate and coupling bolt as well as between the latter and the shaft, the concentricity tolerances are doubled. It would theoretically be conceivable to integrate the cutting plate and the coupling bolt in one piece in order to decrease the tolerances, however, this cutting plate would then be too expensive for use in practice as a wearing part, extremely difficult to handle in technical operations, and production of the cutting plate by sintering technology would be impossible.
EP-B-00 84 607 describes a cutting tool in which the cutting plate has a triangular contour and the front face of the shaft has a recess of complementary form. This cutting tool has proven to be useful in practice, however, with very high cutting performance the danger of breakage exists. Due to the necessary fit tolerance, the cutting plate twists slightly in the plate receiver of the holder and due to the pressure at the edge the projections in the form of chord segments can break off.